Clevertex - Grado Zero Espace Srl

However, next to monitoring device of body parameters, stretch sensors are used as entertainment
device, for instance to control the volume of tracks. A stretch sensor was developed by the Philips
Research Laboratory in Redhill, UK, which can be integrated into a garment. The stretch sensor,
which is produced out of conductive and elastic yarns knitted together, is based on the fact that the
electrical resistance changes with stretching the sensing material. Thus, it can be used to control the
volume of music or changing the track [78].
2.1.3.2 Conductive materials as actuators
During the last 15 years, new polymers have been emerged that respond to an electrical stimulus by
changing either the size or shape. These electroactive polymers (EAPs) can be classified into two
categories according to their actuating capability into
• Ionic EAPs
• Electronic EAPs
Actuators are needed to transform electrical signals into physical phenomena, so that they adapt
themselves to a situation, affect the human body or serve as a display. For example a research group
in the U.S. developed electroactive polymers that change shape and size when stimulated by an
electric current or voltage [44, 45].
De Rossi and his team from University of Pisa are involved in the development of artificial muscles
and skin [46]. Artificial muscles are produced by fibres that are capable to contract when they receive
an electronic signal. His research team develops and uses different types of sensors, generators,
protection systems and other functional analogous structures and devices to mimic properties shown
by biological skins of humans and animals. Such properties include tactile sensing, thermal
sensing/regulation, environmental energy harvesting, chromatic mimetism, ultra-violet protection,
adhesion and surface mediation of mobility [47, 48, 49, 50].
2.1.3.3 Conductive materials as data processing unit
Sauquoit Industries developed a process that enables etching of electronic circuit boards on fabrics
and called it CircuiteX TM . A silver metallised fabric with a fine and dense woven nylon structure offers
the highest level of conductivity. The silver (99.9% pure) permeates the fabric structure to cover all
surfaces of the yarn. A resist is applied to keep the silver in place along the circuit path. Where there is
24